Blepharidium includes one species of terrestrial shrubs and small trees, which are found humid vegetation in southern Mexico and northern Central Amerida. Blepharidium can be recognized by its well developed, triangular, deciduous, interpetiolar stipules, well developed petiolate leaves, axillary inflorescences with several-flowered cymes borne on well developed peduncles, showy 4-merous flowers, well developed white corollas with imbricate lobes, and ellipsoid woody capsules with septicidal dehiscence and winged flattened seeds. The inflorescences have well developed ligulate bracts that are deciduous as the flowers mature. The flowers are homostylous, and their well developed, cylindrical, white corollas suggest they are noctural. The calyx lobes are rounded with wide marginal flanges or lobes, and are unusual in being imbricated. The capsules are often lenticellate and have a distinctive, well developed beak, which forms from the disk; the beak portion is enlarged and woody, and extends above the insertion of the calyx limb so the capsules sometimes has a semi-inferior appearance. The plants are sometimes locally common and form large stands.

See the Flora Mesoamericana treatment for morphological and range details (Lorence et al., 2012; available on the drop-down box on the upper right of this screen), and Standley & Williams (1975: 17-18) for comments on these plants in Guatemala (but there is no illustration there). The capsules split longitudinally along the septum, which has a slit down its middle, and then each valve also splits partially from the top so the capsule has four segments at its top. The capsules were described by Lorence (2012) as splitting shortly and loculicidally first and then deeply and septicidally, and by Standley in the protologue of Blepharidium mexicanum as splitting septicidally first then shortly loculicidally. On dried specimens this sequence apparently varies and many capsules have only four short and equal slits. Capsules with the last form are open only on the top, and appear to have a "salt-shaker" seed dispersal mechanism.

Two species of Blepharidium have been recognized, one in Mexico and one in Guatemala, and local populations are often distinctive in appearance (J. Pollard, pers. comm.). These were separated based on corolla size, the leaves abaxially glabrous vs. sparsely pubescent, and geograpic range, but more specimens now show generally continuous variation with the characters not correlated with each other or geographic distribution. Thus, Lorence et al. (2012) recognized one variable species in the Flora Mesoamericana.

The classification of Blepharidium in the Rondeletieae was supported by Manns & Bremer (2010), and its relationships here are with several other small genera of Mesoamerica and the Antilles (Torres-Montúfar et al., 2017). Blepharidium is similar to Balmea, at least in fruit; Balmea has terminal inflorescences and red to violet corollas with convolute aestivation.

Authors: D.H. Lorence & C.M. Taylor. The content of this web page was last revised on 15 September 2020.
Lorence web page http://ntbg.org/about/staff.php#84
Taylor web page: http://www.mobot.org/MOBOT/Research/curators/taylor.shtml

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